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Development and Phantom Validation of a Small-Form-Factor SWIR Emitter Probe for Hydration-Sensitive Spatial-Ratio
Georgei Farouq1, Devang Vyas2, Amir Tofghi Zavareh1,2,3
1Department of Engineering Technology and Industrial Distribution, Texas A&M University, College Station, TX 77843, USA.
Sensors (Basel, Switzerland)
|April 14, 2026
Summary
A new compact short-wave infrared (SWIR) probe uses LEDs to measure tissue water content non-invasively. This technology enables accurate hydration monitoring for clinical applications like edema detection.
Area of Science:
- Biomedical Optics
- Medical Imaging
- Photonics
Background:
- Non-invasive tissue water content assessment is crucial for clinical applications such as edema detection, fluid management, and inflammation monitoring.
- Short-wave infrared (SWIR) spectroscopy leverages water's absorption bands near 1450 nm and 1650 nm for hydration-sensitive measurements.
- Existing SWIR systems often use bulky spectrometers or high-power sources, hindering development of compact or wearable devices.
Purpose of the Study:
- To develop and validate a compact SWIR diffuse-reflectance probe for non-invasive tissue water content measurement.
- To assess the feasibility of using discrete LEDs and a single photodetector for spatially resolved SWIR measurements.
- To establish a modeling framework for analyzing hydration changes in tissue-mimicking phantoms.
Main Methods:
- A compact SWIR diffuse-reflectance probe was constructed using four discrete LEDs (1450 nm and 1650 nm) and a single photodetector.
- Spatially resolved measurements were acquired at two source-detector separations (4.5 mm and 7 mm).
- Monte Carlo simulations and a diffusion-based forward model were employed for calibration and water-fraction analysis using gelatin-Intralipid phantoms.
Main Results:
- The developed probe demonstrated repeatable and monotonic spatial-ratio signatures correlated with nominal water fraction.
- A mean absolute percent error of 1.55% and a maximum error of 3.33% were achieved under absorption-consistent conditions.
- The system successfully measured controlled hydration changes in tissue-mimicking phantoms.
Conclusions:
- The study demonstrates the feasibility of a compact SWIR ratio sensing system for non-invasive hydration monitoring.
- This technology holds promise for developing portable or wearable devices for clinical applications.
- The provided modeling framework supports future extensions to in vivo measurements.
